RFC#998 - {{fn}} as keyword#21299
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NullVoxPopuli merged 6 commits intoemberjs:mainfrom Apr 8, 2026
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Make the `fn` helper a built-in keyword so it no longer needs to be
explicitly imported in strict-mode templates (gjs/gts).
Building on the infrastructure from RFC#997 ({{on}}), this adds `fn`
to the keywords map and extends the auto-import-builtins AST plugin
to handle SubExpression and MustacheStatement nodes. The existing `on`
rewrite logic is extracted into a shared `rewriteKeyword` helper.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
packages/@glimmer-workspace/integration-tests/test/keywords/fn-test.ts
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Use regular functions instead of helper managers for the fn shadow tests, since only scope shadowing is being verified. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The shadowed fn must return a function since its return value is passed to the on modifier as the callback argument. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Same fix as the integration test — the shadowed fn must return a function since its return value is passed to the on modifier. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
NullVoxPopuli
previously approved these changes
Apr 7, 2026
kategengler
reviewed
Apr 7, 2026
Test fn in attribute position (e.g. <Child @callback={{fn greet "hello"}} />) to cover the MustacheStatement visitor path. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Add empty scope to satisfy the ExplicitTemplateOnlyOptions overload when neither eval nor component is provided. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
kategengler
approved these changes
Apr 7, 2026
This was referenced Apr 8, 2026
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Summary
fnto the built-in keywords map so it no longer needs to be imported in strict-mode (gjs/gts) templatesauto-import-builtinsAST plugin to handleSubExpressionandMustacheStatementnodes forfnrewriteKeywordhelper to reduce duplication with the existingonkeyword logiconPR (RFC#997 - {{on}} as keyword #21068)Implements RFC 0998.
Test plan
fn-test.ts: fn works when explicitly in scope, works with runtime compiler, can be shadowedfn-runtime-test.ts: explicit scope, implicit scope (eval), no eval and no scope (static block)fn-as-keyword-test.gjsandfn-as-keyword-but-its-shadowed-test.gjs🤖 Generated with Claude Code